New maize map to aid plant breeding efforts

The new map, a special type of gene map known as a haplotype map, charts genetic diversity and recombination across the genome of 27 inbred lines of maize. The research team, led by U.S. Department of Agriculture scientists at Cornell University and Cold Spring Harbor Laboratory in New York and including plant scientist Jeffrey Ross-Ibarra of the University of California, Davis, will report its findings in the Nov. 20 issue of the journal Science.

"We are hopeful that the information that this haplotype map reveals about the genetic diversity of maize will provide a foundation for efforts to understand maize evolution and the genetic basis of complex traits that may prove key to maize improvement," Ross-Ibarra said.

Maize (Zea mays L.), with its genome of an estimated 30,000 genes distributed along 10 chromosomes, is about 70 percent the size of the human genome. In constructing the haplotype map, the researchers identified several million genetic variations -- or polymorphisms -- in the DNA sequence among the 27 maize inbred lines, as well as 10-fold to 30-fold variation in the rates at which genes recombine.

"This approach yielded evidence that points to hundreds of regions in the genome that were probably involved in the domestication of maize and-or geographic differentiation among various lines of maize," Ross-Ibarra said."

The research team also included scientists at the University of Missouri, Columbia, and the University of Arizona, Tucson.

Funding for the mapping effort was provided by the National Science Foundation and the U.S. Department of Agriculture.